I need to make a couple trim pieces out of 3/4 x 3/16 half oval brass. It has to be bent on edge into about a 7" radius. Rolling seems to be the best way to do it and I'm thinking I am going to have to make the dies. How critical is the diameter of the die in rolling something like this? Seems like the bigger the better, up to whatever will fit in the roller, but really don't know.